Blast furnace bottom and method of constructing same



I F. M. MILLER 2,413,988

BLAST FURNACE BOTTOM AND METHOD OF CONSTRUCTING SAME Filed June 6, 19443 Sheets-Sheet 1 1947- F. M. MILLER 7 2,413,988

BLAST FURNACE BOTTOM AND METHOD OF CONSTRUC TING' SAME Filed June 6.1944 a Sheets-Sheet 2 r INVENTOR,

Zr dMuMi'uen Jan. 7, 1947. F. M. MILLER 2,413,988

BLAST FURNACE BOTTOI AND IBTHOD OF CONSTRUCTING SUE Filed June 6. 1944 3Shouts-Sheet :5

" INVENI Mlfz'ller; 1 B I Patented Jan. 7, 1947 BLAST FURNACE BOTTOM ANDMETHOD OF I CONSTRUCTING SAME Fred M. Miller, Bala-Cynwyd, Pa., assignorto General Refractories Company, Philadelphia, Pa., a corporation ofPennsylvania Application June 6, 1944, Serial No. 538,907

9 Claims.

The object of the invention is to provide improvements in thecomposition of blast furnace bottoms and the method of constructingsame.

Another and more specific object is to provide in a blast furnace bottoma greater concentration or mass of refractory material within any givenfurnace dimensions, and to insure a more unitary resulting structurethan has heretofore been possible,

Accepted practice heretofore has been to assemble in closest possiblejuxtaposition multiple courses or layers ofaccurately formed brick(usually 18" x 9" x 4 each brick being carefully molded, handled andfired, so as to produce and preserve its desired dimensions and theaccuracy of its corners and edges, even to the extent that they arefrequently ground, in order to insure strictly planularsurfaces andresulting intimate and uniform contact when assembled. However, with allof these precautions it is a practical impossibility to secure such apermanently tight fit and solidarity of the mass, that slight shrinkagetherein will not cause joints to open up and metal to eventually escape.

in line with this effort to obtain exactness and superior workmanship inthe manufacture of blast furnace bottom blocks, emphasis is stressedupon insuring these essential characteristics, with the result thatfiring temperatures have to be regulated to a point where the density ofthe fired blocks usually runs to .a maximum of approximately 1.22 ouncesper cubic inch, since higher firin temperatures tend to cause kilnmarking and a prohibitive degree of distortion, making them unfit forassembly in accordance with present day practices;

A further object, therefore, is to provide a means or method whereb themass or density of blast furnace bottoms may be economically increased,by permitting the practical manufacture of denser bricks or blocks,which can be assembled into a solid mass subject to reduced shrinkage inservice, when and as subjected to furnace operating conditions. Thus,with exactness of workmanship no longer the chief criterion in judgingbottom bricks or blocks, and thefact that they may be more economicallyproduced to securemaximum density with a given raw materiaL'followed byassembly or installation in accordance with the present invention, it isaccordrate an additional 110,000 to 125,000 pounds within the samespace, thereby imparting to the unit structure of refractory materialgreater volume stability and resultinglylongerlife under A givenconditions.

' Still another object, therefore, is toprovide an improved method ofassembly, whereby such high-fired and resultingly dense bottom blocks orbrick, even though considerably distorted, may be incorporated into amatrix of specially prepared ramming mixes to form a solid mass of highoverall density. While refractory ramming mixes are not new, and it iswell known that if properly prepared a high degree of density can beattained, as by ramming with pneumatic tools, such refractory rammingmixes have not heretofore been employed to overcome the difiiculties andproblems which characterize blast furnace bottom construction. Also,instead of constructing a furnace bottom of bricks and fefrac toryramming mixes of the same materials throughout, they may be varied inaccordance with their position or elevation in said bottom, andtherefore with relation to the service to which they are subjectedduring operation of the furnace. For example, one or more of the firstalaid lower courses might comprise intermediate heat duty brickseparatedby Lumnite or Portland cement, the next courses composed ofhigh heat duty brick separated by an intervening ramming mix comprisingpredominantly calcined clay materials, the next course or courses beingcomposed of highfired refractory bricks and intervening ramming mixconsisting of high temperature-resisting materials such as sillimanite,magnesite, or the like, and the one Or more uppermost courses comprisingcarbon blocks separated by a carbon base ramming mix,

The ramming mixes herein referred to comprise calcined materials ingranular form, together with a small proportion of suitable bondingmaterial, and of such analysis that they intimately adhere to theadjacent brick surfaces, and produce a resultingly homogeneous unitarybottom structure having such a high degree of cohesion as to resist theescape of molten metal therethrough, as sometimes occurs.

With the objects thus briefly stated, the inven-' tion comprises furtherdetails of construction, which are hereinafter fully brought out in thefollowing description, when read in conjunction with the accompanyingdrawings, in which Fig. 1

is a vertical, diametrical section through the bash and hearth or cupolasections of a representative type of blast furnace having a bottom ofthe improved coristruction; Fig. 2 is a fragmentary sectionapproximately on the line 2-2 of Fig. 1, with successive courses ofbrick and intervening layers of ramming mix uncovered to varyingdegrees; Fig. 3 shows one method of assembling consecutive rows of brickin a given course, and

the application of the ramming mix therebetween; Fig. 4 is an enlargedfragmentary portion of a given crurse, showing a modified method ofassembling bricks and intervening ramming mix:

Fig. is an extended section on the line 5-5 of Fig. 4; and Fig, 6 is aperspective view of a fragmentary portion of the matrix structure of theramming mix per se, to show among other things the impenetrability ofthe improved bottom construction to molten metal.

Referring to Figs. 1, 2 and 3, the major part of the lower portion of arepresentative type of blast furnace is shown as comprising thecustomary circular bosh and hearth sections I and 2, rev one embodimentof the invention, the full height of said bottom and its foundation arenot shown.

Primarily the furnace bottom is constructed within a cylindricalmetallic casing 4 and a concentric cast iron hearth jacket 5, spacedapart by intervening grouting material 6 of any suitable character, andsurrounded by concrete (and/or brick) reinforcement I, that also servesto support the usual plurality of circumferentially spaced column 8,which support the weight of the lnwall and top sections of the furnaceproper above the mantel Be, as well as the bustle air and water ducts,ore-handling machinery and other super-structure associated therewith.

The said bosh and hearth sections comprise brick walls la and M,respectively, which are interspaced with water-cooled plates 9, whilecircumferentially spaced hot-air nozzles l0 extend through the upperportion of the hearth section to convey to the ore therein air that hasbeen preheated by so-called stoves in well-known manner. The boshsection is probably always conical as to its inner surface, which mergesflush into.

the corresponding surface of the cylindrical hearth section Said hearthsection rests directly upon the bottom 3, which as shown is composed ofany dcsired-number of vertically arranged courses of brick l I, Thesebrick are preferably of substantially the same size for uniformity,regularity of arrangement and easy handling, and are stood on end ineach course but are angularly related.

in adjacent courses. .Also, whereas it has heretofore been consideredessential that broken joints be maintained between bricks in adjacentcourses,

in the present improved construction, broken joints, though maintainedas far as possible following the usual practice, are not so essential,

since adjacent courses are separated by interposed layers ll of theramming mix.

As will be seen from the drawings, which are drawn fairly closely toscale, adjacent bricks in the same course are spaced approximately twoand one-half to three inches apart, or a sufllcient distance to permitthe ready insertion and operation between them of any well known form ofair-driven ramming or tamping tool, while compressing the ramming mix inthe'vertically extending sections l3. By contrast, the thickness of thehorizontal layers of the mix may be of any desired depth, either thesame as, or more or less than, that between the bricks of the samecourse.

Referring to Fig. 3, there is here shown one method of assembling thebricks in the improved construction. An initial row of bricks is laid inspaced relation with one another and Preferably in alignment. Such rowmay be at the center of the hearth bottom coincident with a diameter, ormay be adjacent to one side and coincident with a cord, as for instancethe row of three brick l4. Between the adjacent wall surface and saidbricks while backed by a short beam and between adjacent bricks in thesame row ramming mix is compressed into place, it being noted that withthe improved construction the bricks do not haveto fit the surroundinghearth jacket closely, but instead may leave relatively large spaces l5that are also filled with the mix alone, or with a combination of mixand broken or odd pieces of brick. A

larger beam is then used to back up a second row,

repeated until the point illustrated by Fig. 3 is reached, wherein amuch longer beam I1 is em-- ployed to back up the thirteenth row ofbricks l8, as they are laid in spaced relation with each other and withthe last previous, Or twelfth, row l9. The succession of beams ofgradually increasing length, in one or more sections, is used in reverseorder as the operation progresses through the second half.

The varying lengths of consecutive beams may be secured in fixedposition by any suitable means, which merely for purposes ofillustration is shown in Fig. 3 as comprising a.plurality of blocks 20,which spread the force exerted upon them by jack bars 2| to spacedregions of the said beam. Each of said bars is adjustably positioned inany suitable manner, as for instance, by means of jacks 22, backed orshored by any available timher or the like, such as the central shoringblocks 23 and the single or built-up blocks 24, having diagonal orcurved surfaces 25 for engagement with laterally spaced portions of thejazket 5, said central and lateral blocks being maintained in spacedrelation by compression beams 26, or otherwise as may be desired.Finally, after all of the bricks of a given course have been laid bythis method, a layer 12 of the mix is tamped over and across the entirearea like a blanket, following which another course of brick issuperimposed thereon but preferably arranged at right angles (or atleast angularly) with respect to the bricks of the last completedcourse. This process is repeated until the desired depth or thickness ofthe furnace bottom is attained, whereupon the cylindrical hearth wall 2ais laid thereon in the usual manner, as shown in Fig. 1.

Referring to Figs. 4 and 5, a modified method of laying the brick in agiven course is shown. By this method all of the brick 21 of a givencourse 28 are laid in preferably (though not necessarily) uniformlyspaced upright position upon a layer of mix l2 immediately therebelow.Between the lowermost portions of said brick, both in longitudinal andtransverse directions, are inserted spacing blocks or spacers 30 of anysuitable noncompressible material, such as metal, plastic, ceramic, orotherwise. Upon the opposite sides of said blocks and between saidbricks ramming mix 3| is inserted and rammed or tamped into place by anysuitable tool 3la, whereupon said blocks are lifted and the spaces leftvacant by their removal filled with the mix duly set by ramming. Theblocks are then again inserted between said bricks in the elevatedpositions 32, and more of the mix 33 forced into position between them,and the blocks again lifted, their only one or possibly two elevationsof the spacers may be used, if, preferred, instead of the three heredescribed.

Fig. 6 has been included in order to showthecharacteristics of theramming mix per se after being rammed in a complete bottom, that is, asthough the mix were formed in the absence of the bricks, or the bricksremoved from this fragmentary portion of the composite bottom struc--.

cement mixture rammed between them, a layer of mix upon said course, asecond course of spaced high heat duty brick upon said layer of mix, amix of granular calcined clay materialsrammed between the bricks of saidsecond course, a layer.

of mix upon said second course, a course of spaced high refractory brickupon said second layer, a mix rammed between the bricks of saidlast-mentioned course, and composed of high temperatureresistingmaterials selected from the group consisting of sillimanite andmagne'site, a layer of the same mix material-upon said last-mentionedcourse, a layer of spaced carbon brick-upon said last-mentioned mixlayer, and a carbon-base'mix rammed between said carbon bricks.

2. A furnace bottom, comprising the combination of a course ofintermediate heat duty brick, a course of high heat duty brick, a courseof high refractory brick, a course of carbon brick, and a layer oframmed mix between two adjacent courses.

3. A furnace bottom, comprising the combination of superimposed coursesof refractory brick, the joints between the bricks of each course beingfilled with a mix composed of materials selected from the groupconsisting of silliinanite and magnesite, and a layer of, rammed mixbetween two of the adjacent courses.

4. A furnace bottom, comprising a course of spaced relatively lowheatduty brick, a rammed hydraulic cement mix between the bricks of saidcourse, a layer of a mix covering said course, a second course of spacedhigh heat duty brick upon said layer of mix, a rammed mix of granularcalcined clay materials between the bricks of said second course, alayer of a mix covering said second course, a third course of spacedhigh-fired refractory brick upon said last-mentioned layer, a rammed mixof high temperature-resisting materials selected from the groupconsisting of sillimanite and magnesia-containing material between thebricks of said third course, a rammed layer of the same materialcovering said third course, a fourth course of spaced carbon brick uponsaid last-mentioned layer, and a rammed mix having a carbon baseextending across said fourth course.

5. A furnace construction, comprising superimposed courses of refractorybrick, said courses and the bricks of each course being initially spacedapart, and a ramming mix composed principally of the same material asthat which principally constitutes the material of said brick rammedinto the spaces between adjacent courses and between the bricks of eachcourse, said ramming mix uniting as an integral unit of itself and withthe material of said brick to form a dense, monolithic mass ofsubstantially uniform integral mixture.

6. A monolithic furnace bottom, comprising superimposed courses ofrefractory brick having substantially the same refractorycharacteristics,

said courses and the bricks of each course being initially spaced apart,and a mix composed of material having at least as high refractorycharacteristics as that which constitutes the material of said brickrammed into the spaces between adjacent courses and between the bricksof each course, said mix coalescing with said bricks to form asubstantially integral monolithic structureof substantially uniformdensity throughout said bricks and the intervening mix.

7. The method of constructing a furnace bottom, which consists in layinga course of spaced bricks, ramming between them a, mix havingsubstantially the same refractory characteristics as that of said bricksto attain a density of substantially the same order as that of saidbricks, ramming a layer of similar mix upon said first course, incoalescing engagement with saidfirst mix, laying a second course ofspaced bricks upon said rammed layer, and ramming between the brick ofthe second course a similar mix in coalescing engagement with the mix ofsaid layer, to form an integral monolithic structure of brick and mixhaving substantially uniform density throughout.

8. A monolithic furnace bottom, comprising superimposed courses ofrefractory brick, the

fractory characteristics as that which constitutes the material of thebrick of said uppermost course rammed into the spaces between adjacentcourses and between the bricks of said uppermost course, said mixcoalescing with said bricks to form a substantially integral monolithicstructure in which the bricks of the uppermost course and the rammed mixare characterized by substantially the same density.

9. The method of constructing a furnace bottom of a plurality of brickcourses, which consists in laying a course of spaced brick, rammingbetween said bricks a mix, and upon them a layer of mix in coalescingengagement with the first mix, laying a second course of spaced bricksupon said rammed layer, and a mix between and in a layer upon saidlast-mentioned bricks, the bricks of the uppermost course being ofhigher refractory characteristics than those of the lowermost course,and the mix when rammed being of substantially the same density and atleast as high refractory characteristics as that of the adjacent bricks.

' FRED M. MILLER.

